1. Field of the Invention
The present invention relates to detection systems, and more particularly, to detection systems that can detect an absent or empty container in a diffuser.
2. Description of the Background of the Invention
A multitude of liquid active material emitting devices or diffusers exist in the marketplace. Many of such devices are passive devices that require only ambient air flow to disperse the liquid active material therein. Other devices have a cord and plug extending from the device, a plug extending directly from the device, or batteries, to power elements of the device. In devices having a heater, fan, or other active emitting unit, the user often has no indication that a liquid active material container therein is absent or empty, and therefore the device and its components remain active.
Others have attempted to detect an almost empty condition in a bag or bottle by measuring the capacitance of the contents in the bag or bottle. One such device is attached to a bag or bottle and detects a liquid level of the bag or bottle by detecting a change in capacitance thereof. When the liquid level falls below a specific liquid level, an alarm is generated to signal a user of the condition. Another invention has a capacitance-type fluid level sensor for I.V. and catheter bags. The sensor has conductive plates disposed on an outer surface of a bag to detect a variation in the capacitance of the fluid. When a variation is detected, a comparator determines the level of the fluid. If the fluid is below a threshold level, an alarm signal is provided to an alarm driver.
Another device that detects liquid by measuring the capacitance thereof is an apparatus for detection of liquid incendiaries. The apparatus has a sling supported by first and second supports, wherein two copper strips connected by a conducting wire are attached to the sling. A bottle having contents therein that function as a dielectric medium of a capacitor is disposed in the sling between and in contact with the copper strips. The capacitance of the apparatus changes based on the contents of the bottle, wherein an output signal is generated to indicate the capacitance. When the output signal reaches a predetermined threshold voltage, a light emitting diode (LED) is illuminated.
Other devices use light emitters and light detectors to detect a fluid level in a container. One such device has a light emitter, a light detector disposed adjacent one another near an opening of a container, and a fluid level detector having a light conduit portion, a base surrounding the light conduit portion, two paddles moveably attached to opposite sides of the base, and a biasing member extending between the paddles. Light is emitted through the conduit in the opening and into the container. A reflector disposed on the biasing member reflects the light back through the conduit to the light detector. When the container is full, the biasing member and paddles are biased outwardly. As the container empties, the container begins to collapse, which causes the biasing member and paddles to move inwardly toward one another. Therefore, the reflector is moved away from the conduit, emitter, and detector, thereby varying a path of the light, and thus the intensity of the light received by the detector. The intensity of the light received by the detector is used as an indicator of a fluid amount in the container.
Another device for emitting and controlling the release of volatile materials having an article containing volatile disposed therein has a mechanism that communicates information from the article to the device. The mechanisms have: electrical contacts on or in the article that are capable of being read by electrical circuitry in the device, conductive labeling on or in the article that mates with contacts associated with the device, optical mechanisms including bar coding on the article being read by the device, changes in topography on the article that are capable of being read by sensors in the device, or a radio frequency (RF) identification tag on or in the article that communicates with the device.